The NPOESS sensor suite is based on a long lineage of sensor technology. This lineage extends back to the 1970s. As the value of earth-observing satellites became apparent, they were steadily improved. These improvements included entirely new types of sensors and upgraded versions of existing ones, flown successfully on many satellites. For example, the Visible/Infrared Imager/Radiometer Suite (VIIRS) can trace its technological lineage back through nine different sensors, beginning with the Scanning Radiometer, first flown on ITOS–1 in 1970. The other NPOESS sensors carry similarly rich heritage. This evolutionary approach has reduced development risk while providing usable data sets that can extend far beyond the life of any single satellite.